Knowing a raw bit error rate of a flash device block, or other storage system, is useful for identifying a source of a read failure, such as in a debugging mode. The raw bit error rate helps distinguish between system failures and data corruption due to degraded storage media, sometimes experienced in heavily program/erase cycled flash media. Data corruption can also be due to long retention times and heavy read cycles in the flash media. When the storage device is suffering from severe data corruption and high bit error rates, an error correction coding performed in a read channel will fail to converge. Thus, the error correction coding cannot provide the original data against which the bit error rate is measured. Hence, a technique is desired to use the correction code constraints to roughly estimate the raw bit error rate when the error correction code cannot converge.